Every year many people are killed and many more injured by runaway trailers; trailers that become completely decoupled from the tow vehicle. Runaway trailers are also responsible for large amounts of property damage every year. Primary decoupling occurs when the coupler on the trailer becomes detached from the ball, pintle hook or 5th wheel on the tow vehicle. In most states, state law requires the use of safety chains as a secondary precaution against complete decoupling of the trailer from the tow vehicle in the event the primary coupling fails. Each state has its own laws for trailer safety chains. The state laws are anything but standard and vary considerably from state to state. This can make is difficult for trailer manufacturers to provide safety chains capable of meeting all the state laws. Some of the state laws require that safety chains: have no more slack than necessary, have sufficient strength to control the trailer in the event of a primary decoupling, have strength at least equal to the weight of the loaded trailer, prevent the tow bar from dropping to the ground in the event of a primary decoupling, be crossed under the tongue, may not use the same fasteners as the ball or coupling, cannot be welded to the trailer, must be attached one on each side of the trailer and must meet DOT and SAE standards. Some states do not allow cables in the place of safety chains.
Trailer safety standards for safety chains promulgated by such organizations as the Society of Automotive Engineers (SAE) similarly advocate: two safety chains, each chain having a strength greater than the GVWR of the trailer, the safety chains being permanently affixed-one on each side of the trailer tongue, the two safety chains being crossed under the trailer tongue with about the same slack, the safety chain having no more slack than necessary for turning.
Each of these requirements has a basis in increasing towing safety. In theory, the objective of having safety chains is to be able to maintain the connection between the towing vehicle and the trailer so that both vehicles can safely come to a stop should the primary coupling of the trailer to the tow vehicle fail. For some requirements, the connection between the requirement and the objective is easy to see, such as the chains having sufficient strength to control the towed vehicle in the event of a primary decoupling. The connection of other requirements to the objective is not quite as clear. For instance, crossing the chains under the tongue is supposed to allow the chains to cradle the tongue on top of the chains in the event of a primary decoupling and prevent the tongue from dragging on the ground. Crossing the chains also minimizes the slack required when turning. Minimizing the slack (actually a separate requirement in some states and standards) may keep the tongue from hitting the ground (also a separate requirement in some states and standards) in the event of a primary decoupling. Keeping the tongue from hitting the ground in the event of a primary decoupling allows better control of the trailer as the tongue will not have nearly the tendency to whip side to side, hit road obstacles such as cracks and expansion joints and will reduce the possibility of the trailer ramming into the tow vehicle if the tow vehicle stops faster than the towed vehicle. Additionally, if the tongue does not hit the ground, the safety chains and their connections are much less likely to get ground off thereby reducing the possibility of the trailer becoming completely detached from the tow vehicle. This is also a good safety reason to have the chains attached to the sides of the trailer. Even though some states do not allow them, safety cables (not chains) have also been used for the secondary coupling from the trailer to the tow vehicle. It is very difficult for cables to meet the requirement of no more slack than necessary and keeping the tongue from hitting the ground as will be discussed subsequently. Unless specifically separately designated, deficiencies in the prior art would apply equally to “safety chains” or “safety cables” regardless of which term is used.
Despite regulations and laws designed to prevent runaway trailers, there are still a substantial number of trailers that become completely decoupled from the tow vehicle. The inventor has consulted as an expert in numerous cases where complete decoupling of the trailer has occurred. As a result of misapplication of safety chains, many decouplings have happened and will continue to happen in the foreseeable future.
There are several reasons that primary decoupling occurs including: the coupler was not latched on the ball in the first place; the coupler was latched, but was sitting on top of the ball; the size of the ball did not match the size of the coupler (e.g. a 2″ ball used with a 2 5/16″ coupler); the ball comes loose from the ball mount; the ball mount comes out of the receiver as a result of not being properly pinned in; the kingpin is not properly locked in the 5th wheel hitch or hitch parts are overloaded and break.
Secondary decoupling of the safety chains also occurs for several reasons including: improper, non-gated or weak tow vehicle attachment hooks; nuts and bolts holding a chain end to itself that come loose or fail; chains that have been ground thin as a result of being too long and dragging on the road and then break when put under load; chains or their attachments that get ground off as a result the trailer tongue dragging on the road; chains that break as a result of the trailer whipping back and forth due to excessive safety chain length; reduced strength due to twisting of the chains that is sometimes done to make them shorter; or improperly sized safety chains for the weight of the trailer.
After examining hundreds of trailer safety chains attached to tow vehicles, it has become clear that many, if not most, are attached in a very ineffective manner that could allow for secondary decoupling and that would not meet all state laws and applicable standards. In most cases, the length of the safety chains allow trailer tongue to hit the ground and would allow the trailer to move so far forward in the event of primary decoupling that the trailer can hit the tow vehicle. Many safety chains are attached to the bottom of the trailer tongue.
Although standards and state laws state that chains should be attached to the sides of the trailer tongue, a number of trailer manufacturers have chain attachments located on the bottom of the trailer tongue. This is dangerous when a trailer primary decoupling occurs because these types of attachments have been known to be ground off or allow the chain itself to be ground off as the tongue comes in direct contact with the road at highway speeds. When attached to the bottom of the trailer tongue, chain attachments may be the first point of contact with the road. Even when chains or cables are “protected” by a tube or other device that the cables go through, testing by the inventor has shown that these devices can easily be ground off as they contact the road, exposing the chain or cable to the possibility of being ground off. For example, most grinding wheels operate between 4,000 and 6,500 surface feet per minute, by comparison, 60 miles per hour is 5280 surface feet per minute. When a trailer tongue hits the ground it is roughly equivalent to applying the tongue weight to a gigantic grinding wheel. The results are surprisingly violent, taking only seconds to grind off chains, cables or inches of steel.
Again, many states have laws that state that chains should only have enough slack between the trailer and towing vehicle to allow for the proper turning of tow vehicle and trailer. Trailers usually come with chains or cables that are way too long. This is because the trailer manufacturer makes the trailer chains long enough to be able to attach to many generic tow vehicles with the assortment of hitches used. Some vehicles may have lifts where the chain has to attach to the tow vehicle several feet above the ground. Other smaller tow vehicles may have the safety chain attachment only inches off the ground. There are also different receivers and ball mounts that also change the length chain needed for optimum attachment. In addition, safety chains and cables are not sold (as an aftermarket device) in small length increments so as to have optimum length when used with a specific tow vehicle and trailer. The problem is further exacerbated when multiple tow vehicles are to be used with the same trailer (i.e. companies that rent trailers, companies or individuals that own multiple tow vehicles that might tow the trailer). Many times this means a chain that is too long and drags on the road while driving. Prolonged dragging grinds material off of the chain links and can severely reduce the strength of the safety chains from their rated capacity. Excess slack in the chain can cause a substantial increase in the force required to keep the trailer attached to the tow vehicle in the event of a primary decoupling as the additional length allows the decoupled trailer to swing from right to left behind the tow vehicle. This not only increases the stress on the safety chains but also can cause the tow vehicle to lose control, particularly in instances where the trailer has a high rotational moment of inertia (heavy, long trailers) and the tow vehicle has a light rear axle weight when the trailer is not attached (i.e. pickup trucks). Chains that are too short cannot be attached to the tow vehicle and thus provide no additional security in the event of a primary decoupling. Thus, having safety chains that are either too long or too short results in very dangerous towing conditions.
Sometimes in order to keep the chains from dragging on the ground the chains are twisted many times in order to shorten them. This also weakens the chains. Testing done by the inventor has shown that the chain strength can be decreased by as much as 75% as the links are subject to bending in addition to the normal tensile load as a result of being twisted. Other creative, untested methods of shortening the safety chains may have similar or worse problems
A number of trailer manufacturers have opted to use coiled safety cables in lieu of safety chains because the coil tension shortens the end to end length of the cable, yet the cable can extend to a much longer length. In most cases this eliminates dragging while allowing the safety cable to extend to be able to attach to the tow vehicle and extend during turns. While the ability to coil the cable to shorten it is advantageous for keeping the cables off the ground while towing, in the event of primary decoupling the coiled cable can and will extend to its full length and, in almost every instance, allows the trailer tongue to hit the ground, allows the trailer to swing side to side, and perhaps even allows the trailer to hit the tow vehicle when coming to a stop. Cables are especially susceptible to being ground off should they or their attachments ever come in contact with the ground. Because they are coiled to have extra length on purpose, they virtually never meet the state laws and standards that require them to be “no longer than necessary.” They are virtually never the optimum length (just long enough to allow turns) and thus are a poor method of secondary coupling. Further, they are inferior as they do not lend themselves to being able to change the extended length.
There are a number of patents aimed at addressing the problem of safety chains that are too long and would thus drag on the ground. Much of the prior art has attempted to use safety cables as the solution. Two examples are U.S. Pat. Nos. 6,581,952 and 6,971,661 both of which utilize springs to take up extra slack in a cable. Although this generally keeps the cable off the ground due to the excess slack problem, once the trailer is decoupled the safety cables are pulled to their full length with the attendant safety issues with excessively long cables discussed above. With the housings described in the patent attached to the bottom of the tongue, these systems would be susceptible to being ground off on the road causing the trailer to lose its secondary connection with the towing vehicle. U.S. Pat. No. 5,072,964 also uses a cable that is attached from the trailer directly to the ball. As discussed above one of the reasons for primary decoupling is the ball coming lose. Attaching a cable to the ball would provide no additional secondary decoupling protection for this primary decoupling mode and would not comply with many state laws that require the secondary coupling not to use any of the attachments used by the primary coupling. U.S. Pat. No. 3,608,931 utilizes a chain hook on one end of the chain. A mid portion of the chain is attached to the tow vehicle and then the chain is looped back on itself and the chain hook attached to the chain. A latch keeps the chain hook from disengaging the chain after it has been attached. The downfall of this design is that most times, the attachment holes on the tow vehicle to attach the safety chains to are too small to pass a chain hook through. Therefore, one would have to take the hook off of the chain, pass the chain through the attachment hole and then reattach the hook for this to be used with most receivers. As the hook is generally attached with tools, this is very time consuming and therefore less likely to be done properly. Further, as will be discussed in more detail subsequently, the length of the chain from attachment on the trailer to attachment on the tow vehicle should be minimized to provide the best chance of cradling the tongue in the event of primary decoupling. If the attachment distance is kept very short, as it should be, there is not much latitude for chain length adjustment as done in this patent. Another example is U.S. Pat. No. 3,724,875 which has a cable attached to the bottom of the trailer tongue on a horizontal pulley. This design accounts for the challenges presented when turning. It does not offer the necessary protection in the event of primary decoupling as it is mounted to the bottom of the tongue which is not in accord with the SAE standard and many state laws that require the attachment to be on the side rails of the trailer.
Thus, there is a long felt need for a simple, safe, fast and easy way of properly adjusting the length of safety chains to accommodate the many combinations of tow vehicles, trailers and primary couplings. It is also desirable to have a safety chain attachment system that can be attached to the trailer by the manufacturer that allows the end user to meet all the trail chain laws of their state without having to make substantial changes to the safety chain system. The need to be able to easily and safely adjust the length of safety chains for 5th wheel and gooseneck trailers is similar. The present invention overcomes the deficiencies in the prior art.